1. Field of the Invention
This invention relates to a locking arrangement for locking a drainage grate cover to a utility frame insert which is fitted to a utility access hole or catch basin frame.
2. Description of the Related Art
Road surfaces have numerous openings to permit drainage of rainwater. Typically, the openings are covered with generally rectangular grate covers, which are mounted flush with the road surface. The grate covers are designed to rest on a rectangular flange or rim of a utility access frame, also known and referred to herein as a catch basin frame. Grate cover locking devices are widely used to lock drainage grate covers to their associated catch basin frames.
FIG. 5 illustrates a prior art locking arrangement for a typical grate cover as installed when a roadway is first built. In a typical installation, one side of the grate cover is held in position by a releasable locking device which usually consists of a bolt extending downward from the grate cover. The head of the bolt is accessible from above. As seen in FIG. 5, the opposite side of the grate cover is maintained in position by a metal strap which also engages the underside of the rim on which the grate cover rests. To install the grate cover, the side which includes the strap is inserted first in order to position the strap below the rim. The cover is than pivoted downwardly until the opposite side (the side including the locking device) rests on the rim. During installation, the locking member is rotated to an inward, neutral position (not shown) to avoid interference with the rim. Once the grate is positioned onto the rim, the locking member is then rotated outward to extend beneath the rim and the bolt is tightened. Since the head of the bolt is connected to the grate cover, tightening the bolt serves to clamp the grate cover to the rim.
When roadways are repaved, the grate covers must be raised to the level of the new pavement surface. This is often accomplished by placing a frame insert having a height matching the height of the added paving material on the rim of the catch basin frame and then placing the grate cover on the insert. This solves the problem of raising the grate cover but it renders the existing grate cover lock unusable because the lock bolt can no longer reach beneath the rim of the catch basin frame. Simply lengthening these bolts causes other problems and is not a viable solution.
FIG. 6 illustrates one prior art attempt to solve this problem. In this prior art construction, a notch was machined or formed in the frame insert to define an engagement surface for the lock member. On the side of the insert opposite the side in which the notch or notches were formed, an engagement bar was welded which served as an engagement stop for the metal retaining strap. While this solved the problem, it added a machining step to the manufacture of the frame inserts and has proven to be costly and inefficient. Thus, there is a need for a simple inexpensive solution to the problem.